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  1. #1

    Join Date
    Jul 2010
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    66v with bad piston...what are my best options?

    Gonna try and keep this semi-short for now as I'm posting from my iPhone.

    Anyways - 99 XL1200, according to the display this motor has 120ish hours on it. Piston 1 - the powervalve is gone. Stem is still there. Not even a scratch on the piston, no marks on cylinder, ports, etc. Piston 2 - don't know how/why, there's about a 1/2 inch of the top of the piston (above the top ring land) that's bent up maybe 1/4 inch, right in the middle of where the exhaust port is. No marks on cylinder wall in this one either. Aside from a Solas Concord 13/19, ski is completely stock.

    Things we're planning on doing (ski is shared with my dad) - Riva flame arrestors, carb rebuild (OEM Mikuni as suggested by many on here), rejet carbs with jets from Island Racing, new ride plate, maybe an intake grate, oil blockoff, billet powervalves, d-plate and sensor, and new reeds (unsure which ones).

    My biggest question - what's the best way to go with replacing the bad piston? Honing the cylinder and getting a new piston/rings? Should I just replace all 3 at the same time, or should the others be fine? (still within 5 psi of stock compression) We don't wanna cheap out on anything, moneys not an issue, but at the same time we don't wanna build a 1390. Well...I do...my dad doesn't lol. Also - opinions on other mods? Anything else I should do while I'm in there, or anything I shouldn't do?

    A buddy of mine and I will be doing the work. We're both competent mechanics, not really worried about that unless someone knows of a shop in Houston that would do everything for a good price.

    So much for keeping that short I guess...anyhow, thanks in advance for the advice.


  2. #2

    need help w/ 05 1200 xlt,starting problems, chokeing doesnt help

    ,
    Quote Originally Posted by 1 slow GTO View Post
    Gonna try and keep this semi-short for now as I'm posting from my iPhone.

    Anyways - 99 XL1200, according to the display this motor has 120ish hours on it. Piston 1 - the powervalve is gone. Stem is still there. Not even a scratch on the piston, no marks on cylinder, ports, etc. Piston 2 - don't know how/why, there's about a 1/2 inch of the top of the piston (above the top ring land) that's bent up maybe 1/4 inch, right in the middle of where the exhaust port is. No marks on cylinder wall in this one either. Aside from a Solas Concord 13/19, ski is completely stock.

    Things we're planning on doing (ski is shared with my dad) - Riva flame arrestors, carb rebuild (OEM Mikuni as suggested by many on here), rejet carbs with jets from Island Racing, new ride plate, maybe an intake grate, oil blockoff, billet powervalves, d-plate and sensor, and new reeds (unsure which ones).

    My biggest question - what's the best way to go with replacing the bad piston? Honing the cylinder and getting a new piston/rings? Should I just replace all 3 at the same time, or should the others be fine? (still within 5 psi of stock compression) We don't wanna cheap out on anything, moneys not an issue, but at the same time we don't wanna build a 1390. Well...I do...my dad doesn't lol. Also - opinions on other mods? Anything else I should do while I'm in there, or anything I shouldn't do?

    A buddy of mine and I will be doing the work. We're both competent mechanics, not really worried about that unless someone knows of a shop in Houston that would do everything for a good price.

    So much for keeping that short I guess...anyhow, thanks in advance for the advice.

  3. #3
    need help w/starting 05 1200 yamaha xlt choking doesnt help ,just changed plugs

  4. #4

    Join Date
    Jul 2010
    Location
    Houston, TX
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    13
    Uh...dude...you gotta start your own thread, not reply to someone elses lol

    But just as a thought...spray some starting fluid into the intake and see if it will start/stay running. May be vapor-locked and not getting fuel.

  5. #5

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    WFOPerformance.net or just PM WFO here on the forum.
    TCR

  6. #6
    Happily Self-Employed WFO's Avatar
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    Nov 2005
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    slow GTO

    If you are close to me, I can check the piston to wall clearence on the cyls... that would tell if you need to replace all pistons, or just re-ring the good ones... also I can hone and do all the necessary machine work to build the motor. While you are there it would be a good idea to re-seal the bottom end and inspect and maybe weld the crank.
    There are several things to consider when going this far, and I would be glad to talk to you about them.
    I have all the jets, needles/seats, primer, D-plate, waveeaters, ect in stock for that craft.

  7. #7
    Happily Self-Employed WFO's Avatar
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    Quote Originally Posted by TCR View Post
    WFOPerformance.net or just PM WFO here on the forum.
    TCR
    Thanks Travis

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